Methods of protecting a patient from embolization during surgery

ABSTRACT

The invention provides a nested tubing cannula which comprises outer and inner elongate tubular members, both having a proximal end, a distal end, and a lumen therebetween. The inner tubular member is sealed at its distal end and is nested substantially coaxially within the lumen of the outer tubular member, so that the gap between the inner and the outer tubular member defines a second lumen whereas the first lumen is the lumen of the inner tubular member. A tubular sleeve is disposed coaxially between the inner and outer tubular members. A balloon is mounted on a distal region of the outer tubular member and is in communication with the first lumen. The cannula further comprises a port proximal or distal the balloon occluder and is in communication with the second lumen. Methods for making the devices herein are disclosed.

[0001] This is a continuation of copending application Ser. No.09/455,011, filed Dec. 3, 1999, which is a continuation of copendingapplication Ser. No. 09/286,195, filed Apr. 5, 1999, now U.S. Pat. No.6,042,598, which is a continuation of application Ser. No. 09/022,510,filed Feb. 12, 1998, now U.S. Pat. No. 5,910,154, which is acontinuation of application Ser. No. 08/852,867, filed May 8, 1997, nowU.S. Pat. No. 5,911,734. Each of the above applications and patents ishereby expressly and fully incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates generally to treating plaquedeposits and occlusions within major blood vessels, more particularly toan apparatus and method for preventing detachment of mobile aorticplaque within the ascending aorta, the aortic arch, or the carotidarteries, and to an apparatus and method for providing a stent and afilter in a percutaneous catheter for treating occlusions within thecarotid arteries.

BACKGROUND OF THE INVENTION

[0003] Several procedures are now used to open stenosed or occludedblood vessels in a patient caused by the deposit of plaque or othermaterial on the walls of the blood vessels. Angioplasty, for example, isa widely known procedure wherein an inflatable balloon is introducedinto the occluded region. The balloon is inflated, dilating theocclusion, and thereby increasing intraluminal diameter. Plaque materialmay be inadvertently dislodged during angioplasty, and this material isthen free to travel downstream, possibly lodging within another portionof the blood vessel or possibly reaching a vital organ, causing damageto the patient.

[0004] In another procedure, stenosis within arteries and other bloodvessels is treated by permanently or temporarily introducing a stentinto the stenosed region to open the lumen of the vessel. The stenttypically comprises a substantially cylindrical tube or mesh sleeve madefrom such materials as stainless steel or nitinol. The design of thematerial permits the diameter of the stent to be radially expanded,while still providing sufficient rigidity such that the stent maintainsits shape once it has been enlarged to a desired size.

[0005] Generally, a stent having a length longer than the target regionis selected and is disposed on a catheter prior to use. The cathetertypically has a flexible balloon, near its distal end, designed toinflate to a desired size when subjected to internal pressure. The stentis mounted to the catheter and compressed over the balloon, typically byhand, to assure that the stent does not move as it passes through theblood vessel to the desired location within the patient. Alternatively,self-expanding stents may also be used.

[0006] The stent is typically introduced into the desired blood vesselusing known percutaneous methods. The catheter, having the stentsecurely crimped thereon, is directed to the region of the blood vesselbeing treated. The catheter is positioned such that the stent iscentered across the stenosed region. The balloon is inflated, typicallyby introducing gas or fluid such as saline solution, through a lumen inthe catheter communicating with the balloon. Balloon inflation causesthe stent to expand radially, thereby engaging the stenosed material. Asthe stent expands, the material is forced outward, dilating the lumen ofthe blood vessel.

[0007] Due to substantial rigidity of the stent material, the stentretains its expanded shape, providing an open passage for blood flow.The balloon is then deflated and the catheter withdrawn.

[0008] Because the stent is often constructed from a mesh material, thestent typically compresses longitudinally as it expands radially.Stenotic material trapped between the stent and the vessel wall mayextend into the openings in the mesh and may be sheared off by thislongitudinal compression to create embolic debris free. When thismaterial travels downstream, it can cause serious complications. Forexample loose embolic material released within the ascending aorta, theaortic arch, or the carotid arteries may travel downstream to the brain,possibly causing stroke, which can lead to permanent injuries or evendeath of the patient.

[0009] Thus, there is a need for an apparatus and method for deliveringa stent into an arterial occlusion which substantially reduces the riskof embolic material escaping to the vessel and causing a blockage at adownstream location. There is also an apparatus and method forsubstantially preventing detachment of plaque deposited on the walls ofthe ascending aorta, the aortic arch, the descending aorta, and thecarotid arteries. In addition, there is a need for an apparatus andmethod to substantially contain loose embolic material within the aortaand the carotid arteries during an interventional procedure, preventingit from reaching the brain.

SUMMARY OF THE INVENTION

[0010] The present invention provides an apparatus and method forpreventing embolic material from escaping a site of intervention withinthe aorta, the carotid arteries, and other arteries generally,thereafter causing damage to vital organs, such as the brain. Moreparticularly, the present invention involves an apparatus and method forintroducing a stent into a region of a major blood vessel within thehuman body having plaque deposits, such as the ascending aorta, thedescending aorta, aortic arch, common carotid artery, external andinternal carotid arteries, brachiocephalic trunk, middle cerebralartery, anterior cerebral artery, posterior cerebral artery, vertebralartery, basilar artery, subclavian artery, brachial artery, axillaryartery, iliac artery, renal artery, femoral artery, popliteal artery,celiac artery, superior mesenteric artery, inferior mesenteric artery,anterior tibial artery, and posterior tibial artery, thereby openingocclusions and/or preventing embolic material from breaking free withinthe blood vessel.

[0011] In a first embodiment, the invention includes a guidewire havingan expandable filter attached to it, and a stent catheter. The catheterhas an inflatable balloon mounted on or near its distal end, and aninflation lumen extending through the catheter between a proximal regionof the catheter and the balloon. A stent is provided on the outersurface of the catheter, substantially engaging the balloon. Generally,the stent comprises an expandable substantially rigid tube, sheet, wireor spring, but preferably a cylindrical mesh sleeve. See Palmaz, U.S.Pat. No. 4,733,665, incorporated herein by reference.

[0012] Alternatively, the stent may be a self-expanding sleeve,preferably from nitinol. In this case, the stent catheter does notrequire an inflatable balloon. Instead the stent is compressed over thecatheter and a sheath or outer catheter is directed over the stent tohold it in the compressed condition until time of deployment.

[0013] The guidewire has a filter assembly attached at or near itsdistal end, which includes an expansion frame which is adapted to openfrom a contracted condition to an enlarged condition. Filter material,typically a fine mesh, is attached to the expansion frame to filterundesirable embolic material from blood.

[0014] The guidewire with the expansion frame in its contractedcondition is provided through a sheath or cannula, or preferably isincluded directly in the stent catheter. The catheter typically has asecond lumen extending from its proximal region to its distal end intowhich the guidewire is introduced. The filter assembly on the distal endof the guidewire is then available to be extended beyond the distal endof the catheter for use during stent delivery.

[0015] The device is typically used to introduce a stent into a stenosedor occluded region of a patient, preferably within the carotid arteries.The catheter is introduced percutaneously into a blood vessel and isdirected through the blood vessel to the desired region. If the filterdevice is provided in a separate sheath, the sheath is percutaneouslyinserted into the blood vessel downstream of the region being treated,and is fixed in position.

[0016] The filter assembly is introduced into the blood vessel, and theexpansion frame is opened to its enlarged condition, extending thefilter mesh substantially across the blood vessel until the filter meshsubstantially engages the walls of the vessel.

[0017] The catheter is inserted through the region being treated untilthe stent is centered across the plaque deposited on the walls of theblood vessel. Fluid, preferably saline solution, is introduced throughthe inflation lumen, inflating the balloon, and expanding the stentradially outwardly to engage the plaque. The stent pushes the plaqueaway from the region, dilating the vessel. The balloon is deflated, andthe catheter is withdrawn from the region and out of the patient. Thestent remains substantially permanently in place, opening the vessel andtrapping the plaque beneath the stent.

[0018] When the stenosed region is opened, embolic material may breakloose from the wall of the vessel, but will encounter the filter meshand be captured therein, rather than traveling on to lodge itselfelsewhere in the body. After the stent is delivered, the expansion frameis closed, containing any material captured in the filter mesh. Thefilter assembly is withdrawn back into the sheath or the catheteritself, which is then removed from the body.

[0019] If a self-expanding stent is used, the stent catheter with thecompressed stent thereon is inserted into a sheath, which restrains thestent in a compressed condition. The catheter is introduced into thepatient's blood vessel and directed to the target region. Once the stentis localized across the stenosed region and the filter assembly is inposition, the sheath is drawn proximally in relation to the catheter.This exposes the stent, which expands to engage the wall of the bloodvessel, opening the lumen. The filter assembly is then closed and thecatheter withdrawn from the patient.

[0020] The filter assembly has a number of preferred forms. For example,the expansion frame may comprise a plurality of struts or arms attachedto and extending distally from the distal end of the guidewire. Thestruts are connected to each other at each end and have an intermediateregion which is biased to expand radially. Filter mesh is attachedtypically between the intermediate region and the distal ends of thestruts, thereby defining a substantially hemispherical or conical shapedfilter assembly.

[0021] To allow the filter assembly to be inserted into the lumen of thesheath, the intermediate region of the expansion frame is compressed.When the filter assembly is ready to be introduced into a blood vessel,the guidewire is pushed distally. The expansion frame exits the lumen,and the struts automatically open radially. This expands the filter meshto substantially traverse the vessel. After the stent is delivered, theguidewire is pulled proximally to withdraw the filter assembly. Thestruts contact the wall of the filter lumen, forcing them to compress,closing the frame as the filter assembly is pulled into the sheath.

[0022] In another embodiment, the expansion frame includes a pluralityof struts attached to the distal end of the sheath. The struts extenddistally from the sheath and attach to the distal end of the guidewirewhich is exposed beyond the sheath. At an intermediate region, thestruts are notched or otherwise biased to fold out radially. Filter meshis attached to the struts between the intermediate region and the distalend of the guidewire.

[0023] The filter assembly is directed into position in the bloodvessel, either exposed on the end of the sheath or preferably within asecond sheath which is withdrawn partially to expose the filterassembly. With the sheath fixed, the guidewire is pulled proximally.This compresses the struts, causing them to bend or buckle at theintermediate region and move radially outwardly, expanding the filtermesh across the blood vessel. After use, the guidewire is pusheddistally, pulling the struts back down and closing the filter mesh.

[0024] In an alternative to this embodiment, the struts attached to thedistal end of the sheath and to the distal end of the guidewire arebiased to expand radially at an intermediate region. The filter mesh isattached to the struts between the intermediate region and the distalend of the guidewire. Prior to introduction into a patient, theguidewire is rotated torsionally in relation to the sheath, twisting thestruts axially around the guidewire and compressing the filter mesh.Once in position in the blood vessel, the guidewire is rotated in theopposite direction, unwinding the struts. The struts expand radially,opening the filter mesh. After use, the guidewire is rotated once again,twisting the struts and closing the filter mesh for removal.

[0025] In yet another embodiment, the filter assembly comprises aplurality of substantially cylindrical compressible sponge-like devicesattached in series to the guidewire. The devices have an uncompresseddiameter substantially the same as the open regions of the blood vessel.They are sufficiently porous to allow blood to pass freely through thembut to entrap undesirable substantially larger particles, such as looseembolic material.

[0026] The devices are compressed into the lumen of the sheath prior touse. Once in position, they are introduced into the blood vessel bypushing the guidewire distally. The devices enter the vessel and expandto their uncompressed size, substantially engaging the walls of theblood vessel. After use, the guidewire is pulled proximally, forcing thedevices against the distal end of the sheath and compressing them backinto the lumen.

[0027] In a second embodiment, a stent catheter and filter assembly arealso provided. Unlike the previous embodiments, the filter assembly isnot primarily mechanically operated, but is instead, generally fluidoperated. Typically, the stent catheter includes a second balloon on ornear the distal end of the catheter. A second inflation lumen extendsthrough the catheter from the proximal region of the catheter to theballoon. The balloon is part of the expansion frame or alternativelymerely activates the expansion frame, opening the filter assembly to theenlarged condition for use and closing it after being used.

[0028] In one form, the balloon has an annular shape. Filter mesh isattached around the perimeter of the balloon, creating a conical orhemispherical-shaped filter assembly. A flexible lumen extends betweenthe balloon and the inflation lumen within the catheter. Optionally,retaining wires are connected symmetrically between the balloon and thecatheter, thereby holding the balloon substantially in a desiredrelationship to the catheter.

[0029] When deflated, the balloon substantially engages the periphery ofthe catheter, holding the filter mesh closed and allowing the catheterto be directed to the desired location. Once the catheter is inposition, the balloon is inflated. The balloon expands radially until itengages the walls of the blood vessel, the filter mesh therebysubstantially traversing the vessel. After use, the balloon is deflateduntil it once again engages the perimeter of the catheter, therebytrapping any embolic material between the filter mesh and the outer wallof the catheter.

[0030] Alternatively, the balloon of this embodiment may be provided onthe catheter proximal of the stent for retrograde use. In this case, thefilter mesh is extended between the balloon and the outer surface of thecatheter, instead of having a closed end.

[0031] In a third embodiment of the present invention, a method isprovided in which a stent catheter is used to prevent the detachment ofmobile aortic deposits within the ascending aorta, the aortic arch orthe carotid arteries, either with or without an expandable filterassembly. A stent catheter, as previously described, is provided havingan inflatable balloon and a stent thereon, or alternatively aself-expanding stent and a retaining sheath. The catheter ispercutaneously introduced into a blood vessel and is directed to aregion having mobile aortic plaque deposits, preferably a portion of theascending aorta or the aortic arch.

[0032] The stent is positioned across the desired region, and theballoon is inflated. This expands the stent to engage the plaquedeposits and the walls of the blood vessel, thereby trapping the plaquedeposits. The balloon is deflated, and the catheter is removed from theblood vessel. Alternatively if a self-expanding stent is used, thesheath is partially withdrawn proximally, and the stent is exposed,allowing it to expand. The stent substantially retains its expandedconfiguration, thereby containing the plaque beneath the stent andpreventing the plaque from subsequently detaching from the region andtraveling downstream.

[0033] Optionally, a filter device similar to those already describedmay be introduced at a location downstream of the treated region. Thefilter device may be provided in a sheath which is insertedpercutaneously into the blood vessel. Preferably, however, a filterdevice is attached to the stent catheter at a location proximal to thestent. Instead of attaching the filter assembly to a guidewire, it isconnected directly to the outer surface of the catheter proximal to thestent. A sheath or cannula is typically provided over the catheter tocover the filter assembly.

[0034] Once the catheter is in position within the vessel, the sheath iswithdrawn proximally, the filter assembly is exposed and is expanded toits enlarged condition. In a preferred form, the expansion frameincludes biased struts similar to the those described above, such thatwhen the filter assembly is exposed, the struts automatically expandradially, and filter mesh attached to the struts is opened. After thestent is deployed, the sheath is moved proximally, covering theexpansion frame and compressing the struts back into the contractedcondition. The catheter and sheath are then withdrawn from the patient.

[0035] Thus, an object of the present invention is to provide anapparatus and method for substantially preventing mobile aortic plaquedeposited within the ascending aorta, the aortic arch, or the carotidarteries from detaching and traveling to undesired regions of the body.

[0036] Another object is to provide an apparatus and method for treatingstenosed or occluded regions within the carotid arteries.

[0037] An additional object is to provide an apparatus and method forintroducing a stent to treat a stenosed or occluded region of thecarotid arteries which substantially captures any embolic materialreleased during the procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] For a better understanding of the invention, and to show how itmay be carried into effect, reference will be made, by way of example,to the accompanying drawings, in which:

[0039]FIG. 1 is a longitudinal view of an embodiment being inserted intoa blood vessel, namely a stent catheter in a stenosed region and afilter device downstream of the region.

[0040]FIG. 2 is a longitudinal view of another embodiment, showing thefilter device included in the stent catheter.

[0041]FIG. 3 is a longitudinal view of an embodiment of the filterassembly in its enlarged condition within a blood vessel.

[0042]FIGS. 4A, 4B and 4C show a longitudinal view of an embodiment ofthe filter assembly in a contracted condition, a partially expandedcondition, and an enlarged condition respectively within a blood vessel.

[0043]FIGS. 5A, 5B and 5C show a longitudinal view of another embodimentof the filter device in a contracted condition, a partially openedcondition, and an enlarged condition across a blood vessel respectively.

[0044]FIGS. 6A and 6B are longitudinal views, showing the orientation ofthe filter mesh in an antegrade approach to a stenosed region and in aretrograde approach respectively.

[0045]FIG. 7 is a longitudinal view of another embodiment of the filterassembly.

[0046]FIGS. 8A and 8B are longitudinal views of another embodiment ofthe filter assembly, showing the filter mesh without gripping hairs andwith gripping hairs respectively.

[0047]FIG. 9 is a longitudinal view of another embodiment of the filterassembly including sponge-like devices.

[0048]FIG. 10 is a longitudinal view of another embodiment, namely afilter assembly attached to the outer surface of a stent catheter.

[0049]FIGS. 11A and 11B show a filter assembly attached to the outersurface of a stent catheter, with a sheath retaining the filter assemblyin the contracted condition, and with the filter assembly in theenlarged condition respectively.

[0050]FIGS. 12A and 12B are longitudinal views of another embodimentincluding an inflatable filter assembly, shown in a contracted conditionand an enlarged condition respectively.

[0051]FIG. 13 is a longitudinal view of an inflatable filter assemblyattached to the catheter proximal of the stent shown in an enlargedcondition.

[0052]FIG. 14 depicts a longitudinal view of a stent deployment devicehaving a distal filter disposed within a carotid artery.

[0053]FIGS. 15 and 15A show detailed longitudinal views of a guidewirefilter in accordance with the present invention.

[0054]FIGS. 16, 16A, 16B, and 16C show longitudinal and cross-sectionalviews of an eggbeater filter in accordance with the present invention.

[0055]FIGS. 17 and 17A show longitudinal views of a filter scroll inaccordance with the present invention.

[0056]FIGS. 18, 18A, and 18B show longitudinal views of a filtercatheter in accordance with the present invention.

[0057]FIG. 19 shows an alternate construction for an eggbeater filter asdisclosed herein.

[0058]FIG. 20 shows a longitudinal view of an imaging guidewire havingan eggbeater filter and restraining sheath.

[0059]FIG. 21 shows human aortic anatomy and depicts several routes fordeployment of an aortic filter upstream of the carotid arteries.

[0060]FIG. 22 depicts a longitudinal view of a generalized filterguidewire.

[0061]FIGS. 23 and 23A depict longitudinal views of a compressible,expansible sheath disposed over a guidewire in accordance with thepresent disclosure.

DETAILED DESCRIPTION

[0062] Turning to FIG. 1, a first embodiment of the present invention isshown, namely a stent catheter 10 and a filter device 30. The stentcatheter 10 typically includes a catheter body 12, an inflatable balloon16, and a stent 20. The catheter body 12 typically comprises asubstantially flexible member having a proximal end (not shown) and adistal end 14. The balloon is mounted on a region at or near the distalend 14 of the catheter body 12. An inflation lumen 18 extendslongitudinally from a region at or near the proximal end of the catheterbody 12 to the balloon 16.

[0063] The stent 20 is introduced over the balloon 16, typically bymanually compressing it onto the balloon 16. The stent 20 may comprise atube, sheet, wire, mesh or spring, although preferably, it is asubstantially cylindrical wire mesh sleeve, that is substantially rigid,yet expandable when subjected to radial pressure. Many known stentdevices are appropriate for use with the present invention, such asthose discussed elsewhere in this disclosure. Generally the stent isfurnished from materials such as stainless steel or nitinol, withstainless steel being most preferred.

[0064] Alternatively, a self-expanding stent (not shown) may also beused, such as those disclosed in Regan, U.S. Pat. No. 4,795,458, Haradaet al., U.S. Pat. No. 5,037,427, Harada, U.S. Pat. No. 5,089,005, andMori, U.S. Pat. No. 5,466,242, the disclosures of which are incorporatedherein by reference. Such stents are typically provided from nitinol orsimilar materials which are substantially resilient, yet compressible.When an expandable stent is used, the stent catheter does not generallyinclude an inflatable balloon for the stent. Instead, the stent iscompressed directly onto the catheter, and a sheath is placed over thestent to prevent it from expanding until deployed.

[0065] In addition to the catheter 10, the present invention typicallyincludes a filter device 30. The filter device 30 generally comprises anintroducer sheath 32, a guidewire 40, and an expandable filter assembly50, although alternatively the guidewire 40 and the filter assembly 50may be provided directly on the catheter 10 as will be described below(see FIG. 2). The sheath 32 has a proximal end 34 and a distal end 36,and generally includes a hemostatic seal 38 mounted on its proximal end34. The guidewire 40, typically a flexible, substantially resilientwire, having a distal end 42 and a proximal end 44, is inserted into theproximal end 34 of the sheath 32 through a lumen 33. A hub or handle 46is generally mounted on the proximal end 44 for controlling theguidewire 40.

[0066] Generally, attached on or near the distal end 42 of the guidewire40 is an expandable filter assembly 50 which generally comprises anexpansion frame 52 and filter mesh 60. The expansion frame 52 isgenerally adapted to open from a contracted condition while it isintroduced through the lumen 33 of the sheath 32 to an enlargedcondition once it is exposed within a blood vessel 70, as will bediscussed more particularly below. The filter mesh 60 is substantiallypermanently attached to the expansion frame 52.

[0067] The construction of the stent catheter 10 should already befamiliar to those skilled in the art. The catheter body 12 is typicallymade from substantially flexible materials such as polyethylene, nylon,PVC, polyurethane, or silicone, although materials such as polyethyleneand PVC are preferred. The balloon 16 for delivering the stent 20 isgenerally manufactured from a substantially flexible and resilientmaterial, such as polyethylene, polyester, latex, silicone, or morepreferably polyethylene and polyester. A variety of balloons forangioplasty or stenting procedures are available which have a range ofknown inflated lengths and diameters, allowing an appropriate balloon tobe chosen specifically for the particular blood vessel being treated.

[0068] The sheath 32 for the filter device 30 generally comprises aconventional flexible sheath or cannula for introducing catheters orguidewires into the blood stream of a patient. Exemplary materialsinclude polyethylene, nylon, PVC, or polyurethane with polyethylene andpvc being most preferred. The hemostatic seal 38 generally is an annularseal designed to prevent the escape of blood from the vessel through thesheath 32, and includes materials such as silicone, latex, or urethane,or more preferably silicone. The hemostatic seal 38 is substantiallypermanently adhered to the proximal end 34 of the sheath 32 using knownsurgically safe bonding materials.

[0069] The guidewire 40 is generally manufactured from conventionalresilient wire such as stainless steel or nitinol, although stainlesssteel is preferred, having a conventional hub or handle 46 formedintegral with attached to its proximal end 44.

[0070] Turning now to FIG. 3, the filter assembly 50 of the presentinvention is generally shown extending from the distal end 36 of asheath or catheter 32 and in an enlarged condition within a blood vessel70. The filter assembly 50 includes an expansion frame 52 comprising aplurality of struts, ribs or wires 54, each strut 54 having asubstantially fixed proximal end 56 and a distal end 58, which may ormay not be fixed. The proximal ends 56 are typically connected to thedistal end 42 of the guidewire 40, or alternatively to the outer surfaceof a distal region (not shown in FIG. 3) of the guidewire 40, typicallyusing conventional bonding methods, such as welding, soldering, orgluing. The distal ends 58 of the struts 54 are connected to the filtermesh 60, or alternatively to the distal end of the guidewire (notshown). The struts generally comprise substantially resilient materialssuch as stainless steel or nitinol, with stainless steel beingpreferred.

[0071] Generally, the filter mesh 60 comprises a fine mesh having anopen region 64 substantially engaging the wall 72 of the blood vessel 70and a closed region 62, shown here as the apex of a cone. An appropriatemesh is selected, having a pore size that permits blood to flow freelythrough the mesh, while capturing therein undesired particles of atargeted size. Appropriate filter materials are disclosed in co-pendingapplications Barbut et al., U.S. application Ser. No. 08/553,137, filedNov. 7, 1995, Barbut et al., U.S. application Ser. No. 08/580,223, filedDec. 28, 1995, Barbut et al., U.S. application Ser. No. 08/584,759,filed Jan. 9, 1996, Barbut et al., U.S. application Ser. No. 08/640,015,filed Apr. 30, 1996, Barbut et al., U.S. application Ser. No.08/645,762, filed May 14, 1996, and Maahs, U.S. application Ser. No.08/842,727, filed Apr. 16, 1997. The disclosure of these references andany others cited herein are expressly incorporated herein by reference.An exemplary embodiment of the mesh has a mesh area of 3-8 sq. in., amesh thickness of 60-200 μm, a thread diameter of 30-100 μm, and a poresize of 60-100 μm. Polyethylene meshes, such as Saati Tech and Tetko,Inc. meshes, provide acceptable filter materials, as they are availablein sheet form and can be easily cut and formed into a desired shape. Themesh is formed into a desired filter shape and is sonic welded oradhesive bonded to the struts 54.

[0072] The present invention is then typically used to introduce a stentinto a stenosed or occluded region of a patient, preferably for treatinga region within the carotid arteries. Referring again to FIGS. 1 and 2,the catheter 10 is first introduced into a blood vessel 70 using knownpercutaneous procedures, and then is directed through the blood vesselto the stenosed region of the target blood vessel. The catheter 10 istypically introduced in an upstream-to-downstream (antegrade)orientation as shown in FIGS. 1 and 14, although the catheter may alsobe introduced in a downstream-to-upstream (retrograde) orientation aswill be described below. In a preferred example, the catheter 10 isinserted into a femoral artery and directed using known methods to acarotid artery, as shown in FIG. 14, or alternatively is introducedthrough a lower region of a carotid artery and directed downstream tothe stenosed location 74.

[0073] The sheath 32 is percutaneously introduced into the blood vessel70 downstream of the stenosed region 74, and is deployed usingconventional methods. The distal end 42 of the guidewire 40 is directedthrough the lumen 33 of the sheath 32 until the filter assembly 50 isintroduced into the blood vessel 70 by pushing distally on the hub 46 onthe guidewire 40. When the distal end 42 of the guidewire 40 enters theblood vessel 70, the expansion frame 52 is opened to its enlargedcondition, extending substantially across the entire cross-section ofthe vessel 70. The filter mesh 60 attached to the frame 52 substantiallyengages the luminal walls 72 of the vessel 70, thereby capturing anyundesirable loose material passing along the blood vessel 70 from thetreated region 74.

[0074] The catheter 10 is inserted through the stenosed region 74 untilthe stent 20 is centered across the plaque or embolic material 76deposited on the walls 72 of the blood vessel 70. If the region 74 issubstantially blocked, it may be necessary to first open the region 74using a balloon catheter prior to insertion of the stent catheter (notshown in FIG. 3), as will be familiar to those skilled in the art. Oncethe stent 20 is in the desired position, fluid, saline, or radiographiccontrast media, but preferably radiographic contrast media, isintroduced through the inflation lumen 18 to inflate the balloon 16. Asthe balloon 16 expands, the pressure forces the stent 20 radiallyoutwardly to engage the plaque 76. The plaque 76 is pushed away from theregion 74, opening the vessel 70. The stent 20 covers the plaque 76,substantially permanently trapping it between the stent 20 and the wall72 of the vessel 70. Once the balloon 16 is fully inflated, the stent 20provides a cross-section similar to the clear region of the vessel 70.The balloon 16 is then deflated by withdrawing the fluid out of theinflation lumen 18 and the catheter 12 is withdrawn from the region 74and out of the patient using conventional methods. The stent 20 remainsin place, substantially permanently covering the plaque 76 in thetreated region 74 and forming part of the lumen of the vessel 70.

[0075] As the stenosed region 74 is being opened, or possibly as thecatheter 12 is being introduced through the region 74, plaque may breakloose from the wall 72 of the vessel 70. Blood flow will carry thematerial downstream where it will encounter the filter mesh 60 and becaptured therein. Once the catheter 12 is removed from the treatedregion 74, the expansion frame 52 for the filter mesh 60 is closed tothe contracted position, containing any material captured therein. Thefilter assembly 50 is withdrawn into the lumen 33 of the sheath 32, andthe filter device 30 is removed from the body.

[0076] In another embodiment, shown in FIG. 2, the guidewire 40 and thefilter assembly 50 are included within the stent catheter 10, ratherthan being provided in a separate sheath, thus eliminating the need fora second percutaneous puncture into the patient. As already described,the catheter 12 is provided with an inflatable balloon 16 furnished nearits distal end 14 and with a stent 20 compressed over the balloon 16. Inaddition to the inflation lumen 18, a second lumen 19 extends throughthe catheter 12 from a proximal region (not shown) to its distal end 14.A guidewire 40, having a filter assembly 50 on its distal end 42, isintroduced through the lumen 19 until its distal end 42 reaches thedistal end 14 of the catheter 12. As before, the filter assembly 50comprises an expansion frame 52 and filter mesh 60, which remain withinthe lumen 19 of the catheter 12 until deployed.

[0077] As described above, the stent catheter 10 is percutaneouslyintroduced and is directed through the blood vessels until it reachesthe stenosed region 74 and the stent 20 is centered across the plaque76. The guidewire 40 is pushed distally, introducing the filter assembly50 into the blood vessel 70. The expansion frame 52 is opened to theenlarged condition until the filter mesh 60 engages the walls 72 of theblood vessel 70. The balloon 16 is then inflated, pushing the stent 20against the plaque 76, opening the treated region 74. As before, thestent 20 substantially permanently engages the plaque 76 and becomespart of the lumen 72 of the vessel 70. After the balloon 16 is deflated,the expansion frame 52 of the filter assembly 50 is closed to thecontracted condition, and the filter assembly 50 is withdrawn into thelumen 19. The stent catheter 10 is then withdrawn from the patient usingconventional procedures.

[0078] Alternatively, a self-expanding stent may be substituted for theexpandable stent described above. Generally, the stent is compressedonto a catheter, and a sheath is introduced over the catheter and stent.The sheath serves to retain the stent in its compressed form until timeof deployment. The catheter is percutaneously introduced into a patientand directed to the target location within the vessel. With the stent inposition, the catheter is fixed and the sheath is withdrawn proximally.Once exposed within the blood vessel, the stent automatically expandsradially, until it substantially engages the walls of the blood vessel,thereby trapping the embolic material and dilating the vessel. Thecatheter and sheath are then removed from the patient.

[0079] The filter assembly 50 generally described above has a number ofpossible configurations. Hereinafter reference is generally made to thefilter device described above having a separate sheath, although thesame filter assemblies may be incorporated directly into the stentcatheter.

[0080] Turning to FIGS. 4A, 4B, and 4C, another embodiment of the filterdevice 30 is shown, namely a sheath 32 having a guidewire 40 in itslumen 33 and a filter assembly 50 extending from the distal end 36 ofsheath 32. The filter assembly 50 comprises a plurality of struts 54 andfilter mesh 60. The guidewire 40 continues distally through the filtermesh 60 to the closed end region 62. The proximal ends 56 of the struts54 are attached to the distal end 36 of the sheath 32, while the distalends 58 of the struts 54 are attached to the distal end 42 of theguidewire. In FIG. 4A, showing the contracted condition, the struts 54are substantially straight and extend distally. At an intermediateregion 57, the open end 64 of the filter mesh 60 is attached to thestruts 54 using the methods previously described. The filter mesh 60 maybe attached to the struts 54 only at the intermediate region 57 orpreferably continuously from the intermediate region 57 to the distalends 58.

[0081] In addition, at the intermediate region 57, the struts 54 arenotched or otherwise designed to buckle or bend outwards whencompressed. Between the intermediate region 57 of the struts 54 and thedistal end 36 of the sheath 32, the guidewire 40 includes a lockingmember 80, preferably an annular-shaped ring made of stainless steel,fixedly attached thereon. Inside the lumen 33 near the distal end 36,the sheath 32 has a recessed area 82 adapted to receive the lockingmember 80.

[0082] The guidewire 40 and filter assembly 50 are included in a sheath32 as previously described, which is introduced into a blood vessel 70,as shown in FIG. 4A, downstream of the stenosed region (not shown). Withthe sheath 32 substantially held in position, the guidewire 40 is pulledproximally. This causes the struts 54 to buckle and fold outward at theintermediate region 57, opening the open end 64 of the filter mesh 60 asshown in FIG. 4B. As the guidewire 40 is pulled, the locking member 80enters the lumen 33, moving proximally until it engages the recessedarea 82, locking the expansion frame in its enlarged condition, as shownin FIG. 4C. With the expansion frame 52 in its enlarged condition, theopen end 64 of the filter mesh 60 substantially engages the walls 72 ofthe blood vessel 70.

[0083] After the stent is delivered (not shown), the expansion frame 52is closed by pushing the guidewire 40 distally. This pulls the struts 54back in towards the guidewire 40, closing the open end 64 of the filtermesh 60 and holding any loose embolic material within the filterassembly 50.

[0084] As a further modification of this embodiment, the entire sheath32 and filter assembly 50 may be provided within an outer sheath orcatheter (not shown) to protect the filter assembly 50 duringintroduction into the vessel. Once the device is in the desiredlocation, the sheath 32 is held in place and the outer sheath iswithdrawn proximally, exposing the filter assembly 50 within the bloodvessel 70. After the filter assembly 50 is used and closed, the sheath32 is pulled proximally until the filter assembly 50 completely entersthe outer sheath, which may then be removed.

[0085] Turning to FIGS. 5A, 5B and 5C, another embodiment of the filterassembly 50 is shown. The proximal ends 56 of the plurality of struts 54are substantially fixed to the distal end 36 of the sheath 32. Thedistal ends 58 may terminate at the open end 64 of the filter mesh 60,although preferably, the struts 54 extend distally through the filtermesh 60 to the closed end region 62, where they are attached to thedistal end 42 of the guidewire 40.

[0086] Referring to FIG. 5A, the filter assembly 50 is shown in itscontracted condition. The guidewire 40 has been rotated torsionally,causing the struts 54 to helically twist along the longitudinal axis ofthe guidewire 40 and close the filter mesh 60. The filter assembly 50 isintroduced into a blood vessel 70 as already described, either exposedon the end of the sheath 32 or, preferably, within an outer sheath (notshown) as described above.

[0087] Once in position, the sheath 32 is fixed, and the guidewire 40 isrotated torsionally in relation to the sheath 32. As shown in FIG. 5B,the struts 54, which are biased to move radially towards the wall 72 ofthe vessel 70, unwind as the guidewire 40 is rotated, opening the openend 64 of the filter mesh 60. Once the struts 54 are untwisted, theexpansion frame in its enlarged condition causes the open end 64 of thefilter mesh 60 to substantially engage the walls 72 of the vessel 70, asshown in FIG. 5C.

[0088] After the stent is delivered (not shown), the guidewire 40 isagain rotated, twisting the struts 54 back down until the expansionframe 52 again attains the contracted condition of FIG. 5A. The sheath32 and filter assembly 50 are then removed from the blood vessel 70.

[0089] Another embodiment of the filter assembly 50 is shown in FIGS. 6Aand 6B. The struts 54 at their proximal ends 56 are mounted on or incontact with guidewire 40, and their distal ends 58 are connected toform the expansion frame 52, and are biased to expand radially at anintermediate region 57. The proximal ends 56 are attached to the distalend 42 of the guidewire 40 with the distal ends 58 being extendeddistally from sheath 32. Filter mesh 60 is attached to the struts 54 atthe intermediate region 57. If the filter assembly 50 is introduced inan antegrade orientation as previously described, the filter mesh 60 istypically attached from the intermediate region 57 to the distal ends 58of the struts 54, as indicated in FIG. 6A. Alternatively, if introducedin a retrograde orientation, it is preferable to attach the filter mesh60 between the intermediate region 57 to the proximal ends 56 of thestruts 54, as shown in FIG. 6B, thus directing the interior of thefilter mesh upstream to capture any embolic material therein.

[0090] The filter assembly 50 is provided with the struts 54 compressedradially in a contracted condition in the lumen 33 of the sheath 32 (notshown). The filter assembly 50 is introduced into the blood vessel 70 bydirecting the guidewire distally. As the expansion frame 52 enters theblood vessel, the struts 54 automatically expand radially into theenlarged condition shown in FIGS. 6A and 6B, thereby substantiallyengaging the open end 64 of the filter mesh 60 with the walls 72 of theblood vessel 70. To withdraw the filter assembly 50 from the vessel 70,the guidewire 40 is simply pulled proximally. The struts 54 contact thedistal end 36 of the sheath 32 as they enter the lumen 33, compressingthe expansion frame 52 back into the contracted condition.

[0091]FIG. 8A presents another embodiment of the filter assembly 50similar to that just described. The expansion frame 52 comprises aplurality of struts 54 having a filter mesh 60 attached thereon. Ratherthan substantially straight struts bent at an intermediate region,however, the struts 54 are shown having a radiused shape biased toexpand radially when the filter assembly 50 is first introduced into theblood vessel 70. The filter mesh 60 has a substantially hemisphericalshape, in lieu of the conical shape previously shown.

[0092] Optionally, as shown in FIG. 8B, the filter mesh 60 may includegripping hairs 90, preferably made from nylon, polyethylene, orpolyester, attached around the outside of the open end 64 tosubstantially minimize undesired movement of the filter mesh 60. Suchgripping hairs 90 may be included in any embodiment presented ifadditional engagement between the filter mesh 60 and the walls 72 of thevessel 70 is desired.

[0093]FIG. 7 shows an alternative embodiment of the filter assembly 50,in which the expansion frame 52 comprises a strut 54 attached to thefilter mesh 60. The open end 64 of the filter mesh 60 is biased to openfully, thereby substantially engaging the walls 72 of the blood vessel70. The mesh material itself may provide sufficient bias, or a wireframe (not shown) around the open end 64 may be used to provide the biasto open the filter mesh 60.

[0094] The filter mesh 60 is compressed prior to introduction into thesheath 32. To release the filter assembly 50 into the blood vessel 70,the guidewire 40 is moved distally. As the filter assembly 50 leaves thelumen 33 of the sheath 32, the filter mesh 60 opens until the open end64 substantially engages the walls 72 of the blood vessel 70. The strut54 attached to the filter mesh 60 retains the filter mesh 60 and easeswithdrawal back into the sheath 32. For removal, the guidewire 40 isdirected proximally. The strut 54 is drawn into the lumen 33, pullingthe filter mesh 60 in after it.

[0095] In a further alternative embodiment, FIG. 9 shows a filterassembly 50 comprising a plurality of substantially cylindrical,expandable sponge-like devices 92, having peripheral surfaces 94 whichsubstantially engage the walls 72 of the blood vessel 70. The devices 92are fixed to the guidewire 40 which extends centrally through them asshown. The sponge-like devices have sufficient porosity to allow bloodto pass freely through them and yet to entrap undesirable substantiallylarger particles, such as loose embolic material. Exemplary materialsappropriate for this purpose include urethane, silicone, cellulose, orpolyethylene, with urethane and polyethylene being preferred.

[0096] In addition, the devices 92 may have varying porosity, decreasingalong the longitudinal axis of the guidewire. The upstream region 96 mayallow larger particles, such as embolic material, to enter therein,while the downstream region 98 has sufficient density to capture andcontain such material. This substantially decreases the likelihood thatmaterial will be caught only on the outer surface of the devices, andpossibly come loose when the devices is drawn back into the sheath.

[0097] The devices 92 are compressed into the lumen 33 of the sheath 32(not shown), defining the contracted condition. They are introduced intothe blood vessel 70 by pushing the guidewire 40 distally. The devices 92enter the vessel 70 and expand substantially into their uncompressedsize, engaging the walls 72 of the vessel 70. After use, the guidewire40 is pulled proximally, compressing the devices 92 against the distalend 36 of the sheath 32 and directing them back into the lumen 33.

[0098] Turning to FIG. 10, another embodiment of the present inventionis shown, that is, a stent catheter 10 having a filter assembly 50provided directly on its outer surface 13. The stent catheter 10includes similar elements and materials to those already described,namely a catheter 12, an inflatable balloon 16 near the distal end 14 ofthe catheter 12, and a stent 20 compressed over the balloon 16. Insteadof providing a filter assembly 50 on a guidewire, however, the filterassembly 50 typically comprises an expansion frame 52 and filter mesh 60attached directly to the outer surface 13 of the catheter 12.Preferably, the expansion frame 52 is attached to the catheter 12 in alocation proximal of the stent 20 for use in retrograde orientations,although optionally, the expansion frame 52 may be attached distal ofthe stent 20 and used for antegrade applications.

[0099] The filter assembly 50 may take many forms similar to thosepreviously described for attachment to a guidewire. In FIG. 10, theexpansion frame 52 includes a plurality of radially biased struts 54,having proximal ends 56 and distal ends 58. The proximal ends 56 of thestruts 54 are attached to the outer surface 13 of the catheter 12proximal of the stent 20, while the distal ends 58 are loose. Filtermesh 60, similar to that already described, is attached to the struts 54between the proximal ends 56 and the distal ends 58, and optionally tothe outer surface 13 of the catheter 12 where the proximal ends 56 ofthe struts 52 are attached.

[0100] Prior to use, a sheath 132 is generally directed over thecatheter 12. When the sheath engages the struts 54, it compresses themagainst the outer surface 13 of the catheter 12. The catheter 12 and thesheath 132 are then introduced into the patient, and directed to thedesired location. Once the stent 20 is in position, the catheter 12 isfixed and the sheath 132 is drawn proximally. As the struts 58 enter theblood vessel 70, the distal ends 58 move radially, opening the filtermesh 60. Once the filter assembly 50 is fully exposed within the bloodvessel 70, the distal ends 58 of the struts 54, and consequently theopen end 64 of the filter mesh 60, substantially engage the walls 72 ofthe blood vessel 70.

[0101] After the stent is deployed, the sheath 132 is pushed distally.As the struts 54 enter the lumen 133 of the sheath 132, they arecompressed back against the outer surface 13 of the catheter 12, therebycontaining any captured material in the filter mesh 60. The catheter 12and sheath 132 are then withdrawn from the vessel 70.

[0102] Turning to FIGS. 11A and 11B, an alternative embodiment of theexpansion frame 50 is shown. The proximal ends 56 of the struts 54 areattached or in contact with the outer surface 13 of the catheter 12. Thestruts 54 have a contoured radius biased to direct an intermediateregion 57 radially. Filter mesh 60 is attached between the intermediateregion 57 and the proximal ends 56, or between the intermediate regionand the distal end (not shown). FIG. 11A shows the filter assembly 50 inits contracted condition, with a sheath 132 covering it. The sheath 132compresses the struts 54 against the outer surface 13 of the catheter12, allowing the device to be safely introduced into the patient. Oncein position, the sheath 132 is pulled proximally as shown in FIG. 11B.As the distal end 136 of the sheath 132 passes proximal of the filterassembly 50, the struts 54 move radially, causing the intermediateregion 57 of the struts 54 and the open end of the filter mesh 60 tosubstantially engage the walls 72 of the blood vessel 70. After use, thesheath 132 is directed distally, forcing the struts 54 back against thecatheter 12 and containing any material captured within the filter mesh60.

[0103] In another embodiment of the present invention, shown in FIGS.12A and 12B, a stent catheter 10, similar to those previously described,is provided with a fluid operated filter assembly 50 attached on or nearthe distal end 14 of the catheter 12. The catheter 12 includes a firstinflation lumen 18 for the stent balloon 16, and a second inflationlumen 19 for inflating an expansion frame 52 for the filter assembly 50.The expansion frame 52 generally comprises an inflatable balloon 102,preferably having a substantially annular shape. The balloon 102generally comprises a flexible, substantially resilient material, suchas silicone, latex, or urethane, but with urethane being preferred.

[0104] The second inflation lumen 19 extends to a region at or near tothe distal end 14 of the catheter 12, and then communicates with theouter surface 13, or extends completely to the distal end 14. A conduit104 extends between the balloon 102 and the inflation lumen 19. Theconduit 104 may comprise a substantially flexible tube of materialsimilar to the balloon 102, or alternatively it may be a substantiallyrigid tube of materials such as polyethylene. Optionally, struts orwires 106 are attached between the balloon 102 and the catheter 12 toretain the balloon 12 in a desired orientation. Filter mesh 60, similarto that previously described, is attached to the balloon 102.

[0105] Turning more particularly to FIG. 12A, the filter assembly 50 isshown in its contracted condition. The balloon 102 is adapted such thatin its deflated condition it substantially engages the outer surface 13of the catheter 12. This retains the filter mesh 60 against the catheter12, allowing the catheter 12 to be introduced to the desired locationwithin the patient's blood vessel 70. The catheter 12 is percutaneouslyintroduced into the patient and the stent 20 is positioned within theoccluded region 74. Fluid, such as saline solution, is introduced intothe lumen 19, inflating the balloon 102. As it inflates, the balloon 102expands radially and moves away from the outer surface 13 of thecatheter 12.

[0106] As shown in FIG. 12B, once the balloon 102 is fully inflated toits enlarged condition, it substantially engages the walls 72 of theblood vessel 70 and opens the filter mesh 60. Once the stent 20 isdelivered and the stent balloon 16 is deflated, fluid is drawn back outthrough the inflation lumen 19, deflating the balloon 102. Oncedeflated, the balloon 102 once again engages the outer surface 13 of thecatheter 12, closing the filter mesh 60 and containing any embolicmaterial captured therein. The catheter 12 is then withdrawn from thepatient.

[0107] Alternatively, the filter assembly 50 just described may bemounted in a location proximal to the stent 20 as shown in FIGS. 13A and13B. The open end 64 of the filter mesh 60 is attached to the balloon102, while the closed end 62 is attached to the outer surface 13 of thecatheter 12, thereby defining a space for capturing embolic material. Inthe contracted condition shown in FIG. 13A, the balloon 102substantially engages the outer surface 13 of the catheter 12, therebyallowing the catheter 10 to be introduced or withdrawn from a bloodvessel 70. Once the stent 20 is in position across a stenosed region 74,the balloon 102 is inflated, moving it away from the catheter 12, untilit achieves its enlarged condition, shown in FIG. 13B, whereupon itsubstantially engages the walls 72 of the blood vessel 70.

[0108] A detailed longitudinal view of a filter guidewire is shown inFIG. 15. Guidewire 40 comprises inner elongate member 207 surrounded bya second elongate member 201, about which is wrapped wire 211 in ahelical arrangement. Guidewire 40 includes enlarged segment 202, 208which houses a series of radially biased struts 203. Helical wires 211separate at cross-section 205 to expose the eggbeater filter containedwithin segment 202. Guidewire 40 includes a floppy atraumatic tip 204which is designed to navigate through narrow, restricted vessel lesions.The eggbeater filter is deployed by advancing distally elongate member201 so that wire housing 211 separates at position 205 as depicted inFIG. 15A. Elongate member 207 may be formed from a longitudinallystretchable material which compresses as the struts 203 expand radially.Alternatively, elongate member 207 may be slideably received withinsheath 201 to allow radial expansion of struts 203 upon deployment. Thefilter guidewire may optionally include a coil spring 206 disposedhelically about elongate member 207 in order to cause radial expansionof struts 203 upon deployment.

[0109] A typical filter guidewire will be constructed so that theguidewire is about 5F throughout segment 208, 4F throughout segment 209,and 3F throughout segment 210. The typical outer diameter in a proximalregion will be 0.012-0.035 inches, more preferably 0.016-0.022 inches,more preferably 0.018 inches. In the distal region, a typical outerdiameter is 0.020-0.066 inches, more preferably 0.028-0.036 inches, morepreferably 0.035 inches. Guidewire length will typically be 230-290 cm,more preferably 260 cm for deployment of a balloon catheter. It shouldbe understood that reducing the dimensions of a percutaneous medicalinstrument to the dimensions of a guidewire as described above is asignificant technical hurdle, especially when the guidewire includes afunctioning instrument such as an expansible filter as disclosed herein.It should also be understood that the above parameters are set forthonly to illustrate typical device dimensions, and should not beconsidered limiting on the subject matter disclosed herein.

[0110] In use, a filter guidewire is positioned in a vessel at a regionof interest. The filter is deployed to an expanded state, and a medicalinstrument such as a catheter is advanced over the guidewire to theregion of interest. Angioplasty, stent deployment, rotoblader,atherectomy, or imaging by ultrasound or Doppler is then performed atthe region of interest. The medical/interventional instrument is thenremoved from the patient. Finally, the filter is compressed and theguidewire removed from the vessel.

[0111] A detailed depiction of an eggbeater filter is shown in FIGS. 16,16A, 16B, and 16C. With reference to FIG. 16, the eggbeater filterincludes pressure wires 212, primary wire cage 213, mesh 52, andoptionally a foam seal 211 which facilitates substantial engagement ofthe interior lumen of a vessel wall and conforms to topographicirregularities therein. The eggbeater filter is housed within cathetersheath 32 and is deployed when the filter is advanced distally beyondthe tip of sheath 32. This design will accommodate a catheter of size 8F(0.062 inches, 2.7 mm), and for such design, the primary wire cage 213would be 0.010 inches and pressure wires 212 would be 0.008 inches.These parameters can be varied as known in the art, and therefore shouldnot be viewed as limiting.

[0112]FIGS. 16A and 16B depict the initial closing sequence at across-section through foam seal 214. FIG. 16C depicts the final closingsequence.

[0113]FIGS. 17 and 17A depict an alternative filter guidewire whichmakes use of a filter scroll 215 disposed at the distal end of guidewire40. Guidewire 40 is torsionally operated as depicted at 216 in order toclose the filter, while reverse operation (217) opens the filter. Thefilter scroll may be biased to automatically spring open through actionof a helical or other spring, or heat setting. Alternatively, manual,torsional operation opens the filter scroll. In this design, guidewire40 acts as a mandrel to operate the scroll 215.

[0114] An alternative embodiment of a stent deployment blood filtrationdevice is depicted in FIGS. 18, 18A, and 18B. With reference to FIG. 18,catheter 225 includes housing 220 at its proximal end 221, and at itsdistal end catheter 225 carries stent 223 and expandable filter 224. Inone embodiment, expandable filter 224 is a self-expanding filter deviceoptionally disposed about an expansion frame. In another embodiment,filter 224 is manually operable by controls at proximal region 221 fordeployment. Similarly, stent 223 can be either a self-expanding stent asdiscussed above, or a stent which is deployed using a balloon or otherradially expanding member. Restraining sheath 222 encloses one or bothof filter 224 and stent 223. In use, distal region 226 of catheter 225is disposed within a region of interest, and sheath 222 is drawnproximally to first exposed filter 224 and then exposed stent 223. Assuch, filter 224 deploys before stent 223 is radially expanded, andtherefore filter 224 is operably in place to capture any debrisdislodged during stent deployment as depicted in FIG. 18A. FIG. 18Bshows an alternative embodiment which employs eggbeater filter 224 inthe distal region.

[0115] An alternative design for the construction of an eggbeater filteris shown in FIG. 19. This device includes inner sheath 231, outer sheath230, and a plurality of struts 232 which are connected to outer sheath230 at a proximal end of each strut, and to inner sheath 231 at a distalend of each strut. Filter expansion is accomplished by moving innersheath 231 proximal relative to outer sheath 230, which action causeseach strut to buckle outwardly. It will be understood that the struts inan eggbeater filter may be packed densely to accomplish blood filtrationwithout a mesh, or may include a mesh draped over a proximal portion 233or a distal portion 234, or both.

[0116] In another embodiment, a filter guidewire is equipped with adistal imaging device as shown in FIG. 20. Guidewire 40 includeseggbeater filter 224 and restraining sheath 222 for deployment of filter224. The distal end of guidewire 40 is equipped with imaging device 235which can be any of an ultrasound transducer or a Doppler flow velocitymeter, both capable of measuring blood velocity at or near the end ofthe guidewire. Such a device provides valuable information forassessment of relative blood flow before and after stent deployment.Thus, this device will permit the physician to determine whether thestent has accomplished its purpose or been adequately expanded bymeasuring and comparing blood flow before and after stent deployment.

[0117] In use, the distal end of the guidewire is introduced into thepatient's vessel with the sheath covering the expandable filter. Thedistal end of the guidewire is positioned so that the filter isdownstream of a region of interest and the sheath and guidewire crossthe region of interest. The sheath is slid toward the proximal end ofthe guidewire and removed from the vessel. The expandable filter isuncovered and deployed within the vessel downstream of the region ofinterest. A percutaneous medical instrument is advanced over theguidewire to the region of interest and a procedure is performed on alesion in the region of interest. The percutaneous medical instrumentcan be any surgical tool such as devices for stent delivery, balloonangioplasty catheters, atherectomy catheters, a rotoblader, anultrasound imaging catheter, a rapid exchange catheter, an over-the-wirecatheter, a laser ablation catheter, an ultrasound ablation catheter,and the like. Embolic material generated during use of any of thesedevices on the lesion is captured before the expandable filter isremoved from the patient's vessel. The percutaneous instrument is thenwithdrawn from the vessel over the guidewire. A sheath is introducedinto the vessel over the guidewire and advanced until the sheath coversthe expandable filter. The guidewire and sheath are then removed fromthe vessel.

[0118] Human aortic anatomy is depicted in FIG. 21. During cardiacsurgery, bypass cannula 243 is inserted in the ascending aorta andeither balloon occlusion or an aortic cross-clamp is installed upstreamof the entry point for cannula 243. The steps in a cardiac procedure aredescribed in Barbut et al., U.S. application Ser. No. 08/842,727, filedApr. 16, 1997, and the level of debris dislodgment is described inBarbut et al., “Cerebral Emboli Detected During Bypass Surgery AreAssociated With Clamp Removal,” Stroke, 25(12):2398-2402 (1994), whichis incorporated herein by reference in its entirety. FIG. 21demonstrates that the decoupling of the filter from the bypass cannulapresents several avenues for filter deployment. As discussed in Maahs,U.S. Pat. No. 5,846,260, incorporated herein by reference, a modularfilter may be deployed through cannula 243 either upstream 244 ordownstream 245. In accordance with the present disclosure, a filter maybe deployed upstream of the innominate artery within the aorta by usinga filter guidewire which is inserted at 240 through a femoral arteryapproach. Alternatively, filter guidewire may be inserted through route241 by entry into the left subclavian artery or by route 242 by entrythrough the right subclavian artery, both of which are accessiblethrough the arms. The filter guidewire disclosed herein permits theseand any other routes for accessing the ascending aorta and aortic archfor blood filtration.

[0119] In another embodiment, a generalized filter guidewire is depictedin FIG. 22. FIG. 23 shows guidewire 40 having sleeve 250 disposedthereabout. Sleeve 250 includes longitudinally slitted region 251 whichis designed to radially expand when compressed longitudinally. Thus,when the distal end of sleeve 250 is pulled proximally, the slittedregion 251 buckles radially outwardly as shown in FIG. 23A to provide aform of eggbeater filter. The expanded cage thus formed may optionallyinclude mesh 52 draped over a distal portion, a proximal portion, orboth.

[0120] In use, a stent catheter, such as those previously described, isused in a retrograde application, preferably to prevent the detachmentof mobile aortic plaque deposits within the ascending aorta, the aorticarch, or the descending aorta. Preferably, the stent catheter isprovided with a filter assembly, such as that just described, attachedto the catheter proximal of the stent. Alternatively, a stent catheterwithout any filter device, may also be used. The stent catheter ispercutaneously introduced into the patient and directed to the desiredregion. Preferably, the catheter is inserted into a femoral artery anddirected into the aorta, or is introduced into a carotid artery anddirected down into the aorta. The stent is centered across the regionwhich includes one or more mobile aortic deposits.

[0121] If a filter assembly is provided on the catheter, it is expandedto its enlarged condition before the stent is deployed in order toensure that any material inadvertently dislodged is captured by thefilter. Alternatively, a sheath having a guidewire and filter assemblysimilar to those previously described may be separately percutaneouslyintroduced downstream of the region being treated, and opened to itsenlarged condition.

[0122] The stent balloon is inflated, expanding the stent to engage thedeposits. The stent forces the deposits against the wall of the aorta,trapping them. When the balloon is deflated, the stent substantiallymaintains its inflated cross-section, substantially permanentlycontaining the deposits and forming a portion of the lumen of thevessel. Alternatively, a self-expanding stent may be delivered, using asheath over the stent catheter as previously described. Once the stenthas been deployed, the filter assembly is closed, and the stent catheteris withdrawn using conventional methods.

[0123] Unlike the earlier embodiments described, this method ofentrapping aortic plaque is for a purpose other than to increase luminaldiameter. That is, mobile aortic deposits are being substantiallypermanently contained beneath the stent to protect a patient from therisk of embolization caused by later detachment of plaque. Of particularconcern are the ascending aorta and the aortic arch. Loose embolicmaterial in these vessels presents a serious risk of entering thecarotid arteries and traveling to the brain, causing serious healthproblems or possibly even death. Permanently deploying a stent into suchregions substantially reduces the likelihood of embolic materialsubsequently coming loose within a patient, and allows treatment withoutexpensive intrusive surgery to remove the plaque.

[0124] While the invention is susceptible to various modifications, andalternative forms, specific examples thereof have been shown in thedrawings and are herein described in detail. It should be understood,however, that the invention is not to be limited to the particular formsor methods disclosed, but to the contrary, the invention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the appended claims.

What is claimed is:
 1. A method for open surgery, comprising the steps of: introducing a flexible elongate member into a peripheral artery, the flexible elongate member having a filter on a distal region thereof; advancing the filter to a site within the aorta upstream of a branch vessel from the aorta; deploying the filter; manipulating the aorta by direct access; and removing the filter from the aorta, wherein embolic material is generated and filtered before the blood filter device is removed from the aorta.
 2. The method of claim 1 , wherein the filter is deployed at a region upstream of the site within the aorta.
 3. The method of claim 1 , wherein the branch vessel is the innominate artery.
 4. The method of claim 1 , further comprising the steps of introducing a blood bypass cannula into the aorta.
 5. The method of claim 4 , wherein the cannula is introduced upstream of the site where the filter is deployed.
 6. The method of claim 1 , wherein the step of manipulating the aorta comprises blocking the aorta.
 7. The method of claim 6 , wherein the step of blocking the aorta includes cross-clamping the aorta.
 8. The method of claim 1 , wherein the step of manipulating the aorta comprises unblocking the aorta while the blood filter device is deployed within the aorta.
 9. The method of claim 1 , wherein said elongate member is a catheter.
 10. The method of claim 1 , wherein said elongate member is a guidewire.
 11. The method of claim 10 , wherein said filter is releasably attached to the guidewire.
 12. The method of claim 1 , wherein the peripheral artery is selected from the group consisting of a subclavian artery and a femoral artery. 